Rear end module for passenger motor vehicles

ABSTRACT

The body of passenger motor vehicles comprises, among other things, two longitudinal bearers and a rear end having a rear end middle piece. In order to minimize the extent of repair of damages to the rear end, the invention provides that the rear bumper bending bearer is bolted as a lower module in the area of the rear longitudinal bearer to the body via deformation elements provided for absorbing energy. In order to minimize the complexity of repairs of damages involving a greater extent of deformation to the rear end, the invention additionally provides that the entire rear end middle piece or portions thereof is/are structured as another lower module of the rear end module that can be bolted to the body.

FIELD OF THE INVENTION

The invention relates to a rear end module for passenger motor vehicles,the body of which has two longitudinal members and a rear end with arear end middle piece, with a bumper flexural member that can be boltedto the vehicle body via deformation elements for energy absorption inthe area of the rear longitudinal member.

BACKGROUND OF THE INVENTION

The cost pressures in the automotive industry in general, combined withthe necessity for an economically efficient production, have given riseto considerations of a modular construction of motor vehicles. In thistype of construction, certain components of a vehicle are completelyassembled by suppliers to form modules which together with other modulesare then assembled into a complete vehicle by the vehicle manufacturerusing bolted connections, e.g. in accordance with German Laid OpenPublication DE 38 09 456 A1. This manufacturing concept follows thetrend of increasingly relocating assembly work to the supplier toreduce, among other things, the storage capacities required by thevehicle manufacturer. The cited publication also describes a rear endmodule comprising a rear end trim part, the taillight panel providedwith openings for the taillight assemblies and the separately mountablebumper.

A modular construction of a vehicle is also disclosed in German LaidOpen Publication DE 196 21 451 A1.

This publication describes three typical modules of a motor vehicle. Thefirst module comprises the entire front end. The second module comprisesthe passenger compartment with the front and rear windshield, includingtwo exterior rear fenders molded thereto. A third module, the rear endmodule, is inserted therebetween from behind and the top forming a sealwhen the vehicle is assembled at the vehicle manufacturer's plant. Thisrear end module comprises the entire trunk with the floor part andpossibly a floor well for the spare wheel and, opposite the exteriorfenders, sidewalls to which the taillights are mounted, and the frontand rear end wall of the trunk. The rear bumper, comprising the bumperflexural member bolted to the two longitudinal members and its cover,also forms part of the rear end module.

In addition to the effect of modular construction on the economicefficiency of vehicle production, the ease with which the modules can berepaired is also important for insurance rate classification. Forexample, if the modules are too large, i.e. if they include too manycomponents, the entire module must be replaced after a collision. Thismakes it costly to repair minor damage after an accident.

Today, the repair of vehicles with light to moderate front end collisiondamage is therefore substantially facilitated by relatively small frontend modules in which the front end is divided into components that canbe bolted together, i.e.

-   -   a front structure comprising the headlight assemblies, the        radiator, the hood lock and various other units,    -   a primary structure for specific energy absorption and    -   an outer enclosure, e.g. a bumper apron,

The front structure and the outer enclosure also help absorb energy.

Because the components can be replaced by bolting them into place,costly welding and alignment work is reduced, so that insurers classifythese vehicles in lower full collision rate categories.

For rear end structures, the current practice is to use only smallmodules for specific energy absorption. This rear end module comprisessmall energy-absorbing deformation elements, so-called crash boxes,which in practice are a part of the rear longitudinal member, as well asthe bumper flexural member, which is typically trimmed like a bumper.This rear end module is bolted to the body in the area of the rearlongitudinal member.

Such a rear end module is described, for instance, in German Laid OpenApplication DE 198 31 708 A1.

The invention is based on this type of rear end module.

For space reasons, the so-called rear end middle piece of thebody-in-white structure and other rear end components clearly protrudeover the bolting surfaces of such a rear end module in longitudinalvehicle direction and thereby prevent energy absorption solely throughthe crash boxes. Thus, in case of a rear impact, although thelongitudinal member is kept free from damage by the boltable rear endmodule, the rear end middle piece itself is prematurely deformed becauseof its exposed position.

As a result, undesirable body damage occurs despite the boltable rearend module. This causes costly repairs and has a negative effect on theinsurance classification.

SUMMARY OF THE INVENTION

The object of the invention is to configure the initially described rearend module in such a way as to ensure economically efficient repair evenif the deformation depths are clearly greater than those defined by thecrash boxes.

Based on a rear end module for passenger motor vehicles, the body ofwhich has two longitudinal members and a rear end with a rear end middlepiece, with a bumper flexural member, which can be bolted to the vehiclebody via deformation elements for energy absorption in the area of therear longitudinal member, this object is attained according to theinvention by configuring the entire rear end middle piece or portionsthereof as a submodule that can be bolted to the body.

In the rear end module according to the invention, the scope of thereplaceable boltable components is thus clearly expanded by theintegration of the rear end middle piece. The bolting locations of theentire rear end module relative to the body are now arranged in the areaof the taillight frame, on the rear longitudinal members and in the areaof the lateral parts of the rear end.

The rear end module according to the invention has the followingadvantages:

-   -   Rear impacts cause damage only to boltable parts, even with        clearly greater deformation depths than before.    -   Insurers assign lower collision classification.    -   If the body is made of steel, a different material, e.g.        aluminum, can be used for the rear end module or its submodules        to reduce weight.    -   The module does not need to be painted in the same color as the        vehicle.    -   Different modules can take into account the individual body        types, e.g. sedan, coupe or station wagon.

According to one embodiment of the invention, the rear end module isconfigured as a preassembled unit with preassembled vehicle components,such as taillight light assemblies and trunk lid lock. This embodimentenables an economically efficient assembly of the rear end section ofthe vehicle.

According to a further embodiment of the invention, the rear end moduleaccording to the invention is configured in such a way that the rear endmiddle piece submodule is combined with the bumper flexural member anddeformation element submodule into a complete boltable module that canbe replaced in its entirety.

In case of rear end damage, the entire boltable module can then besimply replaced.

The bumper flexural member and the deformation elements may be damagedas a result of an accident while the rear end middle piece remainsintact. To prevent the total damage from becoming larger because of thecomplete boltable module, a further development of the inventionprovides that the rear end middle piece submodule and the bumperflexural member and deformation element submodule be configured asseparately replaceable boltable modules.

Depending on the deformation depth, the submodules can then be replacedseparately.

According to a further embodiment of the invention, the rear end moduleis preferably configured in such a way that the rear end middle piecesubmodule consists of a partial module including an outer and innercentral rear end cover and a partial module including two rear end sidepanels each adjoining the ends of the central rear end covers. The twopartial modules have extensions and perforated strips, so that thepartial modules can be bolted together.

This embodiment allows cost-effective repairs because it is notnecessary to replace the entire “rear end middle piece” submodule incase of rear end damage with large deformation depth. In case of alateral rear impact it is sufficient to replace the respective rear endside panel. In case of a central rear impact, only the “rear end cover”submodule may have to be replaced.

In an advantageous structural refinement of this further development,the two rear end side panels have two sections that are angled relativeto one another, a rear section and a fender-side section. The rearsection is provided with a perforated strip to that it can be bolted tothe rear end cover submodule. The fender-side section has a perforatedstrip so that it can be bolted to the respective fender.

The partial modules of the “rear end middle piece” submodule can then beinterconnected in a simple manner advantageous for the body structure,before they are joined to the body as a submodule.

To configure the “rear end middle piece” submodule as a preassembledunit and to save additional body parts, this submodule is designed insuch a way that the rear end side panels have openings to receive thetaillight assemblies and that the inner central rear end cover has anopening for the trunk lid lock.

To prevent the rear bumper from protruding too far from the body and tomake it more embedded, the rear end module is preferably configured insuch a way that the outer central rear end cover has an inwardly angledsection to partially accommodate the bumper flexural member anddeformation element submodule and at the two ends is provided with afastening surface to bolt it the longitudinal members.

With respect to the material, the submodules can be stampings made ofsheet steel and/or aluminum for weight reasons. The material-relateddesign may also include some submodule components that are made ofplastic.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail, by way ofexample, with reference to an embodiment depicted in the drawings, inwhich:

FIG. 1 is a perspective view of the rear end section of thebody-in-white of a passenger car with a preferred embodiment of the rearend module according to the invention in its finally assembled state,

FIG. 2 is an exploded view of the submodules and partial modules of therear end module according to FIG. 1,

FIG. 3 is an enlarged detail of FIG. 1 illustrating the finallyassembled rear end module,

FIG. 4 is an exploded view analogous to FIG. 2 showing the submodulesand partial modules of the finally assembled rear end module accordingto FIG. 3,

FIG. 5 is a schematic side view of the rear end section according toFIG. 1 with the finally assembled rear end module,

FIG. 6 is an exploded side view analogous to FIG. 2 showing thesubmodules and partial modules of the rear end module, and

FIG. 7 is an enlarged detail of FIG. 5 depicting the finally assembledrear end module in a side view.

DETAILED DESCRIPTION OF THE INVENTION

The figures of the patent drawings show various views of the rear endsection of a passenger motor vehicle with a modular constructionaccording to a preferred embodiment of the invention.

This modular construction of the rear end section, the rear end modulewith its submodules, has to satisfy the following requirements:

-   -   clearly reduced extent of damage in case of rear end collision    -   reduced weight through increased use of light metal    -   no loss of body rigidity (static or dynamic)    -   no loss regarding endurance strength    -   tightness of joints    -   simple assembly    -   potential for simplified assembly of entire unit in production        process    -   attractive cost/benefit ratio

The rear end module according to the invention satisfies all of theserequirements.

The embodiment of the rear end module according to the inventiondepicted in the figures has a submodule 1 comprising, in a manner knownper se, a bumper flexural member 2, which is enclosed like a bumper by aplastic part 3 (FIG. 6) and elastically yielding deformation elements 4mounted to the bumper flexural member 2. The deformation elements 4 areeach bolted to the two longitudinal members 5 of the self-supportingbody via connecting flanges. For simplicity' sake, the correspondingviews show only the rear end section of the body, with the fenders 6 andthe tank filler neck 6 a, the trunk floor 7 with the spare tire well 7a, the rear window 8 and the trunk lid 9.

The “rear end middle piece” submodule 10 has a plurality of partialmodules: the outer rear end cover 11 and the inner rear end cover 12,which are typically referred to as taillight panels, and two angled rearend side panels 13 forming integrated side cavities, with a rear section13 a and a fender-side section 13 b. Among other things, these partialmodules also form the rear cross member on the body-in-white side.

As the drawings generally show, parts of the body of the rear end middlepiece in the rear end module according to the invention form anadditional submodule, unlike in the conventional rear end module, whichconsists only of the submodule 1, the bumper flexural member and thecrash boxes.

The apron-like angled outer rear end cover 11 has bolting surfaces 11 aat both ends so that, together with the bumper module 1, it can bebolted to the longitudinal members 5. At its upper edge 11 b the outerrear end cover has a groove to receive the profiled sealing member,which seals the trunk lid 9. The lower angled section 11 c provides aclearance to partially receive the bumper module 1 (FIG. 3). The innerrear end cover has an upper support surface 12 a that can be used whenthe trunk is being loaded and a recess 12 b to receive the trunk lidlock. At its two ends, the inner rear end cover has upwardly protrudingflange-type joining sections 12 c to bolt the cover to the rear end sidepanels 13. The inner rear end cover further has a groove-type recess toreceive the profiled sealing member for the trunk lid 9.

The two rear end covers 11, 12 are preferably stampings, i.e. taillightpanels, which can be made of sheet aluminum to save weight. They arepreferably mechanically joined with a boltable partial module, which canbe bolted to the rear end side panels 13. If made of sheet steel, theparts can be mechanically joined by spot welding.

The two rear end side panels 13 form a further partial module of the“rear end middle piece” submodule. Each can be bolted to the rear endsection 13 a having a recess 13 c for the profiled sealing system of thetrunk edge by means of the upwardly protruding connecting sections 12 cof the inner rear end cover 12. On the side section 13 b the rear endside panels have joining strips 13 d for bolting to the fenders, each ofwhich has a bolting strip 6 b. The rear end side panels further haveopenings 13 c to accommodate the taillight assemblies. The rear end sidepanels are preferably also stampings, preferably made of sheet aluminum.However, molded plastic parts can also be used for the partial modules11, 12 and 13.

To produce the vehicles, the partial modules 11/12 and 13 are preferablypreassembled, i.e. bolted together and provided with the taillightassemblies and the trunk lock, before the entire unit, i.e. as a rearend middle piece submodule 10, is bolted to the body. It is alsofeasible to connect the bumper submodule 1 with the rear end middlepiece module 10 to form the rear end module according to the invention,shown in its final state in FIG. 3. In case of a collision with highdeformation depth, the entire rear end module according to FIG. 3 canthen be replaced as a closed unit without costly welding and alignmentwork. It is more advantageous, however, to connect the two submodules 1and 10 so as to be detachable in a nondestructive manner, so that incase of accidents where the rear end middle piece remains intact, onlythe bumper submodule 1 has to be replaced.

The depicted rear end module structure is of course only an example fora specific body type, For other body types, the structural design mustbe adapted to the corresponding type.

1. A rear end module for passenger motor vehicles, a body of which hastwo longitudinal members and a rear end comprising: a rear end middlepiece to which a rear bumper flexural member can be bolted viadeformation elements for energy absorption in the area of the rearlongitudinal members, wherein the rear end module comprises twosubmodules that can be replaced by bolted assembly, a first submodulecomprising the rear bumper flexural member with the deformation elementsand a second submodule comprising the rear end middle piece detachedfrom the body-in-white, with the entire rear end middle piece or partsthereof configured to be bolted to the remaining body-in-white.
 2. Therear end module as claimed in claim 1, wherein the module is configuredas a preassembled unit with preassembled vehicle components.
 3. The rearend module as claimed in claim 2, wherein the preassembled vehiclecomponents are the taillight assemblies and the rear lid lock.
 4. Therear end module as claimed in claim 1, wherein the submodule of the rearend middle piece is combined with the submodule of the bumper flexuralmember and deformation elements into a complete boltable module that canbe replaced as a unit.
 5. The rear end module as claimed in claim 1,wherein the rear end middle piece submodule and the bumper flexuralmember and deformation element submodule are configured as separatelyreplaceable boltable modules.
 6. The rear end module as claimed inclaims 1, the rear end middle piece submodule comprises a partial moduleconsisting of an outer and an inner central rear end cover and a partialmodule consisting of two rear end side panels adjoining the two ends ofthe central rear end cover, wherein the two partial modules haveextensions and perforated strips for bolting the partial modulestogether.
 7. The rear end module as claimed in claim 6, wherein the tworear end side panels have two sections angled relative to one anotherforming integrated side cavities, a rear section and a fender-sidesection wherein the rear section has a perforated strip for bolting tothe partial module of the rear end cover and the fender-side section hasa perforated strip for bolting to the respective fender.
 8. The rear endmodule as claimed in claim 6, wherein the rear end side panels haveopenings to receive the taillight assemblies.
 9. The rear end module asclaimed in claim 6, wherein the inner central rear end cover has arecess for the trunk lid lock.
 10. The rear end module as claimed inclaim 6, wherein the outer central rear end cover has an inwardly angledsection for partially receiving the submodule of the bumper flexuralmember with deformation elements and at the two ends has a mountingsurface each for bolting to the longitudinal members.
 11. The rear endmodule as claimed in claim 1, wherein the submodules have stampings madeof sheet steel or aluminum, or combinations thereof.
 12. The rear endmodule as claimed in claim 11, wherein some components of the submodulesare made of plastic.
 13. The rear end module as claimed in claim 3,wherein the rear end middle piece submodule and the bumper flexuralmember and deformation element submodule are configured as separatelyreplaceable boltable modules.
 14. The rear end module as claimed inclaim 13, wherein the rear end middle piece submodule comprises apartial module consisting of an outer and an inner central rear endcover and a partial module consisting of two rear end side panelsadjoining the two ends of the central rear end cover, wherein the twopartial modules have extensions and perforated strips for bolting thepartial modules together.
 15. The rear end module as claimed in claim14, wherein the two rear end side panels have two sections angledrelative to one another forming integrated side cavities, a rear sectionand a fender-side section, wherein the rear section has a perforatedstrip for bolting to the partial module of the rear end cover, and thefender-side section has a perforated strip for bolting to the respectivefender.
 16. The rear end module as claimed in claim 15, wherein the rearend side panels have openings to receive the taillight assemblies. 17.The rear end module as claimed in claim 16, wherein the inner centralrear end cover has a recess for the trunk lid lock.
 18. The rear endmodule as claimed in claim 17, wherein the outer central rear end coverhas an inwardly angled section for partially receiving the submodule ofthe bumper flexural member with deformation elements and at the two endshas a mounting surface each for bolting to the longitudinal members. 19.The rear end module as claimed in claim 18, wherein the submodules havestampings made of sheet steel or aluminum, or combinations thereof. 20.The rear end module as claimed in claim 19, wherein some components ofthe submodules are made of plastic.